Camshaft insert

ABSTRACT

The invention relates to a camshaft insert for a camshaft, which can be, in particular, a composite camshaft. In this case, the camshaft insert bears an oscillating motor adjuster. An accumulator that can be loaded by means of a spring force is disposed inside camshaft insert. Alternatively, the accumulator can also be disposed in the camshaft.

This application claims the benefit of German patent application no. DE 10 2009 052 841.5-13 filed on Nov. 13, 2009 which is incorporated herein and made a part hereof by reference for all purposes.

BACKGROUND OF THE INVENTION

The invention relates to a camshaft insert for a camshaft, which insert is joined in a rotation-resistant manner to a rotor of an oscillating motor adjuster.

An electrohydraulic valve for an oscillating motor adjuster of a camshaft is already known from DE 100 50 225 A1. This valve is inserted into a valve housing in which channels having work ports A, B are provided, which lead to the pressurized spaces of the oscillating motor adjuster. A tappet of the electrohydraulic valve rests against a piston rod, which is joined in one piece with a piston. This piston can move against a spring force within a pressurized space in the valve housing.

DE 10 2004 038 252 A1 shows an oscillating motor adjuster with a so-called central valve. In a central valve, the valve for actuating the oscillating motor adjuster is disposed radially inside the rotor on the rotor hub thereof.

SUMMARY OF THE INVENTION

The object of the invention is to create an oscillating motor adjuster in which an accumulator is provided in a space-saving manner.

This object is accomplished according to the claimed camshaft insert.

In accordance with the present invention, an accumulator is integrated in a particularly advantageous manner in a camshaft insert, which bears the rotor.

Alternatively, the accumulator can also be disposed in the camshaft.

In one advantageous configuration of the invention, the camshaft insert and a threaded pin are designed in one piece for the rotation-resistant attachment of the rotor to the camshaft. In this way, the camshaft insert can be designed with very thick walls, whereby a lengthwise bore can be introduced into it. In particular, this lengthwise bore can guide the hydraulic fluid, for example motor oil, coming from the accumulator to the central valve. The central valve can thus be designed so that hydraulic fluid is introduced from the lengthwise bore via a small cross bore into an annular groove in the valve piston that is bounded by annular crosspieces. The output edges lie at these annular crosspieces. If these annular crosspieces have the same outer diameter, then the central valve is pressure-compensated.

In a particularly advantageous way, cross bores do not need to lie in the force flow of the threaded connection so that high axial forces can be transferred.

The construction presented according to the invention makes it possible that the regions of the camshaft insert having cross bores for the work ports A, B are kept free of tensile forces, whereby these regions are only loaded with torsional forces when tightening the nut.

In a further advantageous manner, a non-return valve can be provided so that leakage losses are prevented at the rotary leadthrough for the fluid (e.g., motor oil).

Additional advantages of the invention are apparent from the patent claims, the description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like reference numerals denote like elements, and:

FIG. 1 shows the construction of a camshaft drive in a first example embodiment; and

FIG. 2 shows schematically a camshaft drive in a second example embodiment.

DETAILED DESCRIPTION

The ensuing detailed description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an embodiment of the invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.

FIG. 1 shows an example embodiment of a camshaft drive having an oscillating motor adjuster 1, such as has already been presented in DE 100 50 225 A1. In contrast to DE 100 50 225 A1, a hydraulic part 2 of a valve 3 is designed as a central valve. The oscillating motor adjuster 1 comprises a stator 4 driven by a crankshaft or another camshaft via a gearing 48. For this purpose, a chain, a toothed belt or another toothed gear engages in this gearing 48. In addition, oscillating motor adjuster 1 comprises a rotor 6, which is disposed so that it can it pivot relative to stator 4. For this purpose, blades 49 of rotor 6 subdivide chambers of stator 4 (which are not shown in more detail) into opposite-working pressure chambers.

The camshaft drive comprises a camshaft 5, which is mounted on both sides in camshaft bearings, which are not shown in further detail. This camshaft 5 has cams (not shown in further detail), with which cylinder valves of an internal combustion engine can be actuated. Camshaft 5 is designed as a composite camshaft. In this case, the basic unit of camshaft 5 is a hollow pipe, onto which the cams are shrunk or press-fitted. In the end on the side of the oscillating motor, a fitting piece 7 is machined in the inside space of the hollow shaft that takes up an inner pin 8 of a camshaft insert 9.

Outside camshaft 5, the camshaft insert 9 is shaped as a rotor support 10, which has a larger diameter than inner pin 8. At the rear end, camshaft insert 9 has a threaded pin 11, the threaded diameter of which is smaller than the diameter of rotor support 10. A nut 12, which braces rotor 6 in a rotation-resistant manner against a shoulder 13 of rotor support 10, is screwed onto this threaded pin 11. For this purpose, an annular projection 15 that projects to the inside radially from a rotor hub 14 is braced axially between nut 12 and shoulder 13 of camshaft insert 9. This shoulder 13 forms the boundary between rotor support 10 and threaded pin 11. Rotor hub 14 is placed on the back region of rotor support 10.

In contrast, the front region of rotor support 10 projects through a bearing piece 16 of a cylinder head part 17, which supportively holds this rotor support 10. In this case, an annular groove 18 is worked into cylinder head part 17, this groove being introduced from an oil pump for motor oil, which is not shown in more detail, so that this annular groove 18 forms a pressurized connection P. A strip-shaped, no-return valve 50 is inserted into this annular groove 18, which prevents motor oil from being able to flow back into the oil pump as a consequence of camshaft alternating torque. The pressurized motor oil is fed into a cross bore 19 of rotor support 10 by this pressurized connection P. The flow of motor oil is distributed from this cross bore 19 that passes through onto an accumulator 20 and a lengthwise bore 21 in rotor support 10 that leads to valve 3. This lengthwise bore 21 is sealed at its end pointing toward the inside space of the engine by means of a bead 22 that is pressed in.

Accumulator 20 is aligned coaxially to its central axis 23 in a front region of camshaft insert 9. A pressurized space 24 of accumulator 20 is formed by a blind hole 25, which is worked into camshaft insert 9 from the front. A hydraulic piston 26, which is joined in a movement-resistant manner with a piston rod 27 in a direction pointing away from pressurized space 24, is introduced in an axially movable manner in this blind hole 25. This piston rod 27 projects with radial play through a ring 28, which is solidly pressed into inner pin 8 in the entrance region of blind hole 25. One end of a screw-type pressure spring 29 is supported on this ring 28, and the other end thereof is supported on hydraulic piston 26. The radial play between piston rod 27 and ring 28 makes possible the passage of air or motor oil, so that hydraulic piston 26 is freely movable without the circumstance that the volume that is being displaced from a spring space results in flow resistances that are too high. In this way, accumulator 20, that can be loaded by means of a spring force, is formed.

A hydraulic part 2 is disposed flush with this accumulator 20 in camshaft insert 9. A separating wall 30 lies between accumulator 20 and hydraulic part 2. One end of another screw-type pressure spring 31 is supported on this separating wall 30, and the other end thereof is supported at a bottom 32 of a valve piston 33. For this purpose, this other end projects into a guide recess 34 of valve piston 33 up to the base of this recess, in which lies bottom 32.

Valve piston 33 is guided axially in a central blind hole 35. Blind hole 35 opens up in the region of threaded pin 11. In this case, the entrance region of this blind hole 35 forms the first tank outlet T1.

Valve piston 33 has a wide annular groove 36, so that annular crosspieces 37, 38, each of which forms output edges 39, 40, 41, 42 on both sides, remain on both side of annular groove 36. Output edges 40, 41 that face each other thus serve for the run-in to a work port A or B. Output edges 39, 42 facing away from each other form the run-off to a tank outlet T1 or T2.

Motor oil can be introduced into annular groove 36 via a cross bore 43. This cross bore 43 is provided in wall 44 of rotor support 10 and thus forms the storage connection S. Cross bore 43 crosses lengthwise bore 21. In this way, storage connection S is joined via the frontmost cross bore 19 with both pressurized space 24 as well as with pressurized connection P.

A space 45, which leads to the second tank outlet T2 via a cross bore 46, is axially enclosed between valve piston 33 and separating wall 30. This second tank outlet T2 lies axially between cylinder head part 17 and oscillating motor adjuster 1. Further, this second tank outlet T2 lies axially

-   -   between storage connection S, on the one hand, and     -   the two work ports A, B and the pressure connection P, on the         other hand.

A tappet 47 of an electromagnetic linear actuator, which is shown by dashes, but not in further detail, lies outside, i.e., projecting out from the entrance region, on valve piston 33.

If tappet 47 is maximally disengaged or moved out, then the motor oil coming from annular groove 36 is guided via work port A into the pressure chambers of oscillating motor adjuster 1, these chambers being assigned to a first direction of rotation. In contrast, the motor oil is guided out of the pressure chambers assigned to the opposite direction of rotation to first tank outlet T1 via the work port B. In this way, rotor 6 together with camshaft 5 turns opposite stator 4 in the first direction of rotation.

In contrast, if tappet 47 is maximally engaged or moved in, then the motor oil coming from annular groove 36 is guided via work port B into the pressure chambers of oscillating motor adjuster 1 assigned to the other direction of rotation. Likewise, the motor oil is guided out of the pressure chambers assigned to this other direction of rotation to second tank outlet T2 via the work port A. In this way, rotor 6 together with camshaft 5 turns opposite stator 4 in the other direction of rotation.

In this way, the play between valve piston 33 and blind hole 35 is dimensioned in a ratio to the axial distances between work ports A, B and output edges 39 to 42 such that in a central position of valve piston 33, pressure is provided on the pressure chambers assigned to both directions of rotation. In the central position, consequently, the hydraulic pressure is controlled with a slight overlap. Hydraulic piston 26 in accumulator 20 need not absolutely have a piston rod 27. If the guide length of hydraulic piston 26 is sufficient, the entire diameter can also be utilized in ring 28 for a large flow volume.

Since the camshaft has a relatively slow speed, balancing errors play a subordinate role. However, in order to reduce the balancing error, the lengthwise bore and the cross bores in the camshaft insert can be distributed around the periphery so that the balancing error is only slight.

If an opening is provided in bottom 32 of valve piston 33, then blind hole 35 can also be closed, so that the pressure relief vis-à-vis the tank only occurs via the one tank outlet T2, which thus forms the single tank outlet. In this case, the tappet projects through a sealed opening in camshaft insert 9.

Hydraulic piston 26 can also be guided directly in camshaft 5, if the latter is designed with a hollow tube as the basic unit.

Ring 28 may also be directly supported axially in camshaft 5.

Strip-shaped, non-return valve 50 may also be inserted into an annular groove in camshaft insert 9. In this way, leakage losses can be prevented from occurring at the transfer point from bearing piece 16 to camshaft insert 9.

One possible embodiment of a strip-shaped, non-return valve is shown in U.S. Pat. No. 7,600,531 B2.

FIG. 2 shows the hydraulic diagram of an example embodiment of a camshaft insert 57 with integrated non-return valve 63 in an alternative embodiment.

In this embodiment, the oscillating motor camshaft adjuster 51 is constructed analogously to the first embodiment discussed above in connection with FIG. 1. However, in the FIG. 2 example embodiment, the transfer point of the motor oil from a cylinder head part 52 at an annular groove 53 is disposed axially between an electromagnetic actuator 54 and the oscillating motor camshaft adjuster 51. Camshaft insert 57 thus projects out as a pin 59 above oscillating motor camshaft adjuster 51. In this way, pin 59 is taken up in cylinder head part 52. A channel 61 coming from an oil pump 60 leads into a bore 62, which guides the motor oil into annular groove 53 of camshaft insert 57. From annular groove 53, the motor oil is guided via non-return valve 63, on the one hand, to an accumulator 58 and, on the other hand, to a valve piston 55.

Analogously to the first embodiment, this valve piston 55 is supported axially on camshaft insert 57 by means of a screw-type pressure spring 56. Valve piston 55 is also aligned flush relative to accumulator 58, which, as is shown in FIG. 2, can be disposed directly in camshaft insert 57. Alternatively, accumulator 58 can also be disposed in the camshaft.

The described embodiments only involve exemplary configurations. A combination of the described features for the different embodiments is also possible. Additional features, particularly those which have not been described, of the device parts belonging to the invention can be derived from the geometries of the device parts shown in the drawings.

List of Reference Symbols

-   1 Oscillating motor camshaft adjuster -   2 Hydraulic part -   3 Valve -   4 Stator -   5 Camshaft -   6 Rotor -   7 Fitting piece -   8 Inner pin -   9 Camshaft insert -   10 Rotor support -   11 Threaded pin -   12 Nut -   13 Shoulder -   14 Rotor hub -   15 Projection -   16 Bearing piece -   17 Cylinder head part -   18 Annular groove -   19 Cross bore -   20 Accumulator -   21 Lengthwise bore -   22 Bead -   23 Central axis -   24 Pressurized space -   25 Blind hole -   26 Hydraulic piston -   27 Piston rod -   28 Ring -   29 Screw-type pressure spring -   30 Separating wall -   31 Screw-type pressure spring -   32 Bottom -   33 Valve piston -   34 Guide recess -   35 Blind hole -   36 Annular groove -   37 Annular crosspiece -   38 Annular crosspiece -   39 Output edge -   40 Output edge -   41 Output edge -   42 Output edge -   43 Cross bore -   44 Wall -   45 Space -   46 Cross bore -   47 Tappet -   48 Gearing -   49 Blade -   50 Non-return valve -   51 Oscillating motor camshaft adjuster -   52 Cylinder head part -   53 Annular groove -   54 Electromagnetic actuator -   55 Valve piston -   56 Screw-type pressure spring -   57 Camshaft insert -   58 Accumulator -   59 Pin -   60 Oil pump -   61 Channel -   62 Bore -   63 Non-return valve 

1. A camshaft insert for a camshaft, which is joined in a rotation-resistant manner to a rotor of an oscillating motor adjuster, wherein an accumulator that can be loaded by means of a spring force is disposed inside the camshaft insert.
 2. The camshaft insert according to patent claim 1, further comprising a hydraulic part of a valve disposed radially inside the rotor.
 3. The camshaft insert according to patent claim 2, wherein the hydraulic part is disposed flush relative to the accumulator.
 4. The camshaft insert according to claim 2, wherein the accumulator is separated from the hydraulic part by means of a wall, on which a first end of a screw-type pressure spring is supported, at least indirectly, a second end of the spring being supported on a valve piston.
 5. The camshaft insert according to patent claim 4, further comprising an electromagnetic actuator supported on one side of a valve piston and the second end of the screw-type pressure spring is supported on the other side of the valve piston, whereby fluid is introduced into the valve piston via a storage connection (S) coming from the accumulator, the fluid being able to be divided onto two work ports (A, B) alternately via two output edges by means of an overlap control, and the work ports leading into opposite-working pressure chambers on both sides of at least one blade of the rotor.
 6. The camshaft insert according to claim 1, wherein the accumulator has a pressurized space into which the fluid is introduced from a pressurized connection (P).
 7. The camshaft insert according to patent claim 6, wherein the accumulator is bounded by an axially movable hydraulic piston, which is supported thereon at an axial part attached to the camshaft on a side pointing toward pressurized space by means of a screw-type pressure spring.
 8. The camshaft insert according to patent claim 7, wherein the fluid is introduced into the accumulator from a channel to which is introduced the fluid from an annular groove, which is provided in a cylinder head part.
 9. The camshaft insert according to claim 5, wherein a tank connection (T2) lies axially between a pressurized connection (P) leading into a pressurized space of the accumulator and the work ports (A, B).
 10. The camshaft insert according to claim 1, wherein: the camshaft comprises a hollow camshaft; and the camshaft insert has an inner pin, which is pressed into the hollow camshaft.
 11. The camshaft insert according to patent claim 10, wherein the camshaft comprises a composite camshaft.
 12. The camshaft insert according to patent claim 11, wherein the camshaft insert and a threaded pin for fastening the rotor in a rotation-resistant manner on the camshaft are designed in one piece.
 13. The camshaft insert according to claim 1, wherein the camshaft insert has a threaded pin onto which is screwed a nut, which braces the rotor in a rotation-resistant manner against a shoulder of the camshaft insert.
 14. The camshaft insert according to claim 1, further comprising a non-return valve positioned in the hydraulic flow between an oil pump and the accumulator.
 15. A camshaft insert for a camshaft, which is joined in a rotation-resistant manner to a rotor of an oscillating motor adjuster, wherein an accumulator that can be loaded by means of a spring force is disposed in the camshaft.
 16. The camshaft insert according to patent claim 15, further comprising a hydraulic part of a valve disposed radially inside the rotor.
 17. The camshaft insert according to patent claim 16, wherein the hydraulic part is disposed flush relative to the accumulator.
 18. The camshaft insert according to claim 16, wherein the accumulator is separated from the hydraulic part by means of a wall, on which a first end of a screw-type pressure spring is supported, at least indirectly, a second end of the spring being supported on a valve piston.
 19. The camshaft insert according to patent claim 18, further comprising an electromagnetic actuator supported on one side of a valve piston and the second end of the screw-type pressure spring is supported on the other side of the valve piston, whereby fluid is introduced into the valve piston via a storage connection (S) coming from the accumulator, the fluid being able to be divided onto two work ports (A, B) alternately via two output edges by means of an overlap control, and the work ports leading into opposite-working pressure chambers on both sides of at least one blade of the rotor.
 20. The camshaft insert according to claim 15, wherein the accumulator has a pressurized space into which the fluid is introduced from a pressurized connection (P).
 21. The camshaft insert according to patent claim 20, wherein the accumulator is bounded by an axially movable hydraulic piston, which is supported thereon at an axial part attached to the camshaft on a side pointing toward pressurized space by means of a screw-type pressure spring.
 22. The camshaft insert according to patent claim 21, wherein the fluid is introduced into the accumulator from a channel to which is introduced the fluid from an annular groove, which is provided in a cylinder head part.
 23. The camshaft insert according to claim 19, wherein a tank connection (T2) lies axially between a pressurized connection (P) leading into a pressurized space of the accumulator and the work ports (A, B).
 24. The camshaft insert according to claim 15, wherein: the camshaft is a hollow camshaft; and the camshaft insert has an inner pin, which is pressed into the hollow camshaft.
 25. The camshaft insert according to patent claim 24, wherein the camshaft comprises a composite camshaft.
 26. The camshaft insert according to patent claim 25, wherein the camshaft insert and a threaded pin for fastening the rotor in a rotation-resistant manner on the camshaft are designed in one piece.
 27. The camshaft insert according to claim 15, wherein the camshaft insert has a threaded pin onto which is screwed a nut, which braces the rotor in a rotation-resistant manner against a shoulder of the camshaft insert.
 28. The camshaft insert according to claim 15, further comprising a non-return valve positioned in the hydraulic flow between an oil pump and the accumulator. 